grammaticality - 'In the event of fire' or 'in the event of a fire'?

1. In the event of fire,...



2. In the event of a fire,...

I see both variants ondifferent Web pages and I cannot understand which is correct.

Could you please explain it to me.

Answer

In my understanding it should be:

"In case of a fire",is correct; implying that if there is the occurrence or the instance of a fire breaking out...

My feeling is that "in case of fire", may have started as an attempt at brevity and may have been integrated into everyday usage over time.